Switching device in wave guide transmission system



July. 1, 1947. w. A. TYRRELL SWITCHING DEVICE IN WAVE GUIDE TRANSMISSION SYSTEM FiledMaroh 25, 1944 Vi5 Sheets-Sheet l lll INVENTOR mAfrR/efu we 5ML.;

July l, 1947. l w. A. TYRRELL.

SWITCHING DEVICE IN WAVE GUIDE TRANSMISSION SYSTEM Filed March 25, 1944 3 Sheets-Sheet 2 /NVENTOR @y WAJVRRE/.L Wl ci ATTORNEY RELAT/VE TRANSMISSION IN BEC/@ELS RELATIVE TRANSM/.SS/ON IN DEC/@ELI July l, 1947.

VANE ANGLE ROTAT/ON /N DEGREES (ARE/TRAIN' REFERENCE) I CHANNEL N0. 2

CHANNEL N0. l

W. A. TYRRELL SWITCHING DEVICE IN WAVE GUIDE'TRANSMISSION SYSTEM Filed March 25, 1944 f 3 Sheets-Sheet 5 I I I I I I I I I I I I I I I I I I 1.- 9.6 cu; 2%" ou. of' CLEARANCE :Plc:

l I l n l l I l I l l I I I I l l y WAJ'IRRELL AroR/VEV Patented July 1, '1947 SWTTCHING DEVICE IN WAVE GUIDE TRANSMISSION SYSTEM Warren A. Tyrrell, Fairhaven,

N. J., assignor to i Bell Telephone Laboratories, Incorporated, New

York, N. Y., a corporation of New York Application March 25, 1944, Serial No. 528,118

15 Claims.

This invention relates to Wave guide transmission systems and particularly to wave switching arrangements for use in such systems.

An object of the invention is to eiliciently control wave transmission in a wave guide transmission system.

A more specific object is to switch in an enicient manner the flow of electromagnetic wave power from one wave guide branch to another in a branching wave guide transmission system.

These objects are attained in accordance with the invention by the use of a switching device employing resonant coupling irises and associated mechanical meansior detuning the irises, operating in combination as valves either to allow or substantially prevent transmission of electromagnetic Wave energy of a given frequency through the irises between associated wave guide transmission lines.

In `one embodiment of the invention such as switching device is adapted for switching electromagnetic wave energy oi' a given frequency received over a main dielectric wave guide line into either one of two branching dielectric wave guide lines which respectively comprise hollow metal pipes. The switching device includes two metal plates of suitable size each containing two correspondingly situated, oppositely disposed, irises (suitably dimensioned slots) of optimum shape for efcient switching, each proportioned so as to be resonant at the given frequency, the plates being assembled with an inner metal spacer ring and outer metal anges so as to provide good metallic contact between each plate and the ring and an electrically shielded narrow clearance space between the plates. A sectoral metal vane is adapted for rotation within the clearance space past the two sets of aligned resonant irises in the two plates in turn. The switch assembly is mounted between adjacent ends of the main guide and the two branch guides with one of its plates aflixed to the periphery and extending completely across the cross-section of the main guide and the other plate aiiixed to the peripheries and extending completely across the cross- 1 Sections of the two branch guides; and the irises in the two plates are positioned so that the interior of the main guide is connected to the interior of one branch guide through one set of aligned irises and to the interior of the other branch guide through the otherset of aligned irises. When the vane is rotated so that a portion of it is in a given position between either set of resonant irises and no portion is between the other set of resonant irises, the first set is capacitively detuned so as to substantially prevent transmission of electromagnetic wave energy of the given frequency to the associated branch guide from the main guide and the other set is maintained tuned to transmit substantially all of the wave energy of that frequency from the main guide to the other branch guide.

The important advantages ofthe switching device of the invention may be summarized as-folparts which are small and of light weight so that; the cost of operation and maintenance is low;

(5) its construction is inherently simple, and is not at all critical as to dimensions so that it is amendable to punch-press construction methods Vwhich reduce the cost of manufacture; and (6) its valve action is such that the blocking of each branch wave guide channel is characteristic of a fixed virtual piston, which makes it particularly suitable for use in an antenna lobe switching system, for example, such as disclosed inthe copending patent application of A. C. Beck, Serial No. 455,322 filed August 19, 1942,- which issued as Patent No. 2,409,183 on October 15, 1946.

The various features and advantages of the switching arrangement of the invention will be better understoodlfrom the following detailed description when read in conjunction with the accompanying drawings, in which:

Fig. l shows diagrammatically how the switching device of the invention would be applied for switching wave power in a wave guide transmission system;

Fig. 2 shows a perspective assembly viewv of a portion of a dielectric wave guide transmission system embodying a switching arrangement in accordance with-the invention; j

Fig. 3 showsa perspective exploded view of the arrangement of Fig. 2 illustrating the component parts of the switch and associated wave guide elements more clearly;

Figs. `4 and 5 respectively show a longitudinal sectional view along the line 5-5 and a crosssectional view' along the line 44, of the switch and wave guide assembly of Fig. 2, illustrating certain construction details more clearly;

Figs. 6a to 6j show progressive steps in the development of a preferred resonant iris arrangementl for the switching device of the invention, such as illustrated in Figs. 2 to 5; and

Figs. rI and 8 show curves indicating qualita- 5 tively theperformance of typalvswitching def vices in accordance withlthe invention-L As a preliminary to the detailed description'of one` embodiment of the invention, it is believed that the following general discussion of resonantrl irises may be helpful to provide anninderstanClingzY of the operation of the switching deviner2 .Y The discussion will be limited to resonant iris action in connection with the dominant-wavepropagated .3

in'dielectric wave guides, althoughlsit" isltoebe `l5 j understood that the considerations may be extended to include other wave typesby.malringrape-1 propriate changes in the constructions.

If a dielectric Wave guide is interrupted by av metal plate or partition extending across its crosssectionand-whichimakesgood-rnetalliccom tact withfthe-peripheryoff `the guide,LA all= of the l propagated-wave power incidentV uponethe platerr willi be"freflected.l If -the fwave-guide is reprel sented ias -a transmission '-line, the-plate-may Lbe represented'asl arr electrical short-'circuitI acrossy the line.Y Nowyif anapertureeis-made-in= suchfa plateifreiection of '-allofl the 'incident-power -will be preyentedfA l ang-1? some will be i transmitted throughth'e aperture'. It theaperturecomprises afslotvhavingits" 'long fgdimensi'on y paraller .tofthe electri-cvectorof-the dominant propagatedfwavegf and "extending Icompletely facross the --wave guide;

the slotted-plate aoross-theguidelmay -loe consid-f ered Aas 1the -equivalentyof-an inductance in shunt`l withagtrans-missionj line; whereas if =the-slot exf-v tendscompletely'acrossl theeguide inra 'direction'V perpendicular to the linesof electricforce lof: the propagateddominant wavaethe eife'ct will' be sim'-, ilrtogthat- Lproduced'Il oy-a capacitance `:inf-shunt a" trans-mission'- lii-ie. Inffei'ther-casefthe amountofpower-transmitted through-'the slot will dependmarkedly-upon' -th'e lwdtlafof the slotz and willflce *small-fori -a Ln'arrcvvfslo'ti I :a f rectangular lslot` isfcutv irl-'the VUplate so x as nottofextendfcompletely-:tothe periphery of' the waveguidehinieitherdirectionthe lresultantl effect isisirnillr tofthat produced-byfaninductance and a L; capacitance# respectively connectedy int`r shunt- Withgan'equivalenttransmission line at the .samepints-- These-tweshunt elementsmay bepinHgen-y eral,`A combinedv as ashuntglreactanceethe -sign f of whiehfis dependent onf-Which tof# the itwoorig'inalv shunt` elements." predominatesfi. l-e., whichfis `lower inrimpedances One-casepffespecial'- importance irirconnection with'the -presenteinventioni islth'ati fone in: lwhich' the proportions ofithe sloteare '-suchi that. the shunt. reaotance 10i' the i icapacitance @equals the shuntzfreactanceot-theinductance.: Inzthis case,v paraliebresonance results andthe :equivalent im= pedanceof the combination, that is to`say;-ofthe slotted =plateg ispurely-1 resistvie fat a r:given-frequencydcomprising V:only fthe resistance incidental tothe'twosoriginalpredomiriantlyreactive' shunt elements. The magnitudeof this shuntv resistance willdepenellfnponJ thevwidtl'iof -the "slot and. also uponithethickness of thesplate in=`whichfthe slot isicut.; Bysaproper-fchbiceof the width'andlthick; ness, the resistance willibefsufliciently high'fsothatthere-willfbefno:appreciabldteiectrat .the frequency *iat Lwhichtheparallelz resonance #occurs Iriwjcth'er..wordsfalthough:.theslotA isfafvery :con-f` siderable geometrical;disoontinuitygit is in-reali-ty essentially :transparent #for-the-waves'- Although v energy `tube. controlledl:

`reactance.

the slotted plate displays parallel resonance only for a given frequency, by a proper choice of the slot width the impedance may be made so high as not to interfere appreciably with the transmission of wave power over a band of frequencies. It will be noted that, as the slot is narrowed, the limittis aninnitely narrow-:slot one-half wava length'long, having its long dimension-'perpendia ular to the lines of electric intensity.

A parallel tuned slot, to be referred to hereinafter;- as ,'aeresonant iris, may be considered as a meansfforwcompressing wave power of the resonant frequency into a small cross-section without materially interfe'r-ring with the power flow. ln the switching devices, of the present invention, the resonant-irises are used for this purpose and a Valveiactionvfisprovided by causing the wave powenof the resonant frequency, in its highl37 compressed condition, to be intercepted by small suitably shaped metal vane.

InS the :above -discussionpreference was .made .to

the thickness of 'thefmetal 'slottedfplates it isv to be understood v.that :their thicknessesarevvery` small compared with the wavelength;of th`e=wave is :made thicker, the inductance :L otthelslot will decrease .exactly =in.:proportion1 tozthe. .increase sin*` its eapacitancefCg; so ithat the product LCf.-re-^ mains substantially aconstant;` thus, vforfrelatively tliinipla'testthe resonantafrequencyis:independent ofrthe1 plate.thickness.. Thisfact greatly Simplie'sthef; obtaining fof "appropriate airis. dimensions for-J af.: particular, application'a involving thick plates', inasmuchfas;thefpreiiminary'work may .be

The type iof valveA yusedin ,thezarrangement--. :of

thepresent invention; therefore; may be regarded asia fresonantiris the. aperture of which canbe at; :least partially ,blockedcbypa metall vane. f. At this; point, it; is desirable 4tto gpoint: .out.:that the valve action; may. be regar-.dedicas` taking v place .byeitheroffrtwo mechanisms-9- Thepower flow prof ceedssubstantially .withoutr disturbance across a narrowtclearance f space or vgap between two resonantv irises; and l the metal .vane Amaybe regarded as .la means for interrupting this power ow= geo-y metrically. Alternatively,v the actionf'of `such -a vane may y-be considered: as :ameans forvcapacitivelydetuning..a `resonant iristo substantially shift its resonant Wavelength, so that at the'operating.l wavelengththeiris appears as 'a 'lowifshunt From' the Vformer pointv 'of' View; the eect offa metal. vane ona-resonantiris'vwillzdependupon how much-.fshadow it casts upc-n Vthe irispthat.ispuponfhow large -a portion ofgtheslot it. overlapsyvhen viewedfrom a point' behind the vane von axlinefperpendicular .tothe planes of the slotiand,vane. From the lelectrica-Lcircuit vpoint offiview, z,the .effectiveness of the ,vanedepends upon howmuch additionalfcapacitance is effec; tively, introducede-by :it into ther iris. .1, Inasmuch as ;thef;ca1:1acitance..` iss. effectively vconcentrated neanthe :center Vofl the slot; this latterf :viewpoint explains whyg a vane which-appears -to :block only partially vvmay. z becsof. effective. It'. also' explains whyfthe clea1.anceiA between thevanel andfthe iris plates -in'` the embodiment. 'offthefinvention' 't0;;be

If agivenslot 'in aplate. of given thickness is resonant, then as. the .'platc.

2,42a1 so described later in connection with the drawings must'be kept small. The electrical circuit point of view is the more exact, the geometrical interruption `or shadow concept having been introduced merely to give a clearer qualitative understanding of the valve action.

As stated previously, the simplest form of resonant iris is a straight slot a half wavelength long. The slot, however, may be distorted into a great variety of shapes each of which by proper proportioning may be made resonant at the desired frequency. Some of these shapes may be preferable for enhancing the cut-off or 4snap action of the valve comprising the resonant iris and associated detuning vane, i. e., for increasing the blocking effect due to a small movement of the vane. In particular, if the slot is so designed so as to include two portions which are approximately radial relative to the axis of rotation oi the vane, the leading edge of a sectoral vane will have a most pronounced effect in blocking the flow of power. Figs. 6a to Gf show progressive stepsin the distortion of a simple resonant iris to provide respectively greater improvement in the snap action of such valve, the orientation of the electric intensity of the electromagnetic wave transmission being indicated by the vector E` in each case. Fig. 6a shows a plate with a straight rectangular slot (iris) cut in it; Fig. 6b the slot bent sharply at the center to provide two straight portions; Fig. 6c the slot bent to provide three straight portions; Fig. 6d the slot bent to form ve straight portions; and Fig. 6e a preferred slot derived from the slot of Fig. 6d by eliminating all sharp angles. The elimination of the sharp angles is desirable to facilitate the passage of high Apower or high peak power through the resonant iris without corona discharge in the slot, For the same reason, it is desirable to choose an iris plate thick enough so that an acceptable curvature may also be introduced in the longitudinal dimensions of the iris. The curvilinear length of the resonant irises shown in Figs. 6a to 6e maynot be the same for the same resonant frequency.

Fig. 6j shows two resonant irises of the type shown in Fig, 6e oppositely disposed on the iris plate. A similar construction is used in each iris plate of the embodiment of the invention illustrated in Figs. 2 to 5, in which two such valves as described above are combined to provide a switch.

Figs, 2 to 5 show a detailed embodiment, drawn full scale, of a switching device in accordance with the invention embodying the principles discussed above, applied to al wave guide transmis sion system of the general type illustrated in Fig. l for switching electromagnetic wave energy received over a single main wave guide from a suitable wave generator into any one oi a plurality of branch wave guides, the case or two branch wave guides being chosen for specic illustration. For convenience, the main wave guide line I in the `system of Figs. 2 to 5 has been shown as comprising a circular metal pipe, and the two branch wave guide lines 2 and 3 as comprising rectangular metal pipes, although the associated switching device in accordance with the invention is adapted for use with any type of tubular conductor for the main and branching lines.

The switching device 4 as shown in Figs. 2 to 5 includes as assembly of two metal iris plates 5 and 5, a relatively thin metal annular spacer 'ring I separating the iris' plates and providing good metallic contact with the plates, and two outer flange plates 8 and 9. The assembly of iris plates, spacer ring and ilange plates are held tightly together by the bolts I0 so as to form an electrically shielded, cylindrical clearance space II between the iris plates and spacer ring, the longitudinal dimension of which is quite small. In each iris plate 5 and 6, there are two correspondingly situated, oppositely disposed. resonant irises I2, I3 and I2', I3', each comprising a curvilinear slot having its long dimension per pendicular tothe vector E representing the direction of the lines of electric intensity of the dorninant electromagnetic wave transmitted over the associated main wave guide 2, and proportioned so that it is resonant to the given frequency f of that wave. For the reason given previously, each of these curvilinear slots is preferably shaped so as to include two portions which are radial relative to the longitudinal axis of the main wave guide. The switching device 4 also includes a small sectoral metal vane I4 of a thickness slightly smaller than the longitudinal thickness of the clearance space II adapted to be rotated therein past the aligned resonant irises I2, I2' and I3, I3' in the two plates in turn, about an axis coaxial with the longitudinal axis of the main wave guide I, by means of the shaft or axle i5 mounted in bearings I6, and extending into the clearance space II through openings in the centers of flange plate 9 and iris plate 5. The dimensions of the clearance space I I are preferably made such as to provide only suflicient room to allow the vane to rotate freely in it to the desired positions with respect to the resonant irises.

'Ih'e switch assembly 4 is inserted between adjacent ends of the main wave guide I and the branch guides 2 and 3 with the outer face of iris plate 5 affixed with good metallic contact to the periphery of main guide I and extending completely across its end cross-section, and with the outer face of the other iris plate 6 afiixed with good metallic contact to the peripheries of the two branch guides 2 and 3, and extending completely across the end cross-sections of both branch guides. The irises in the iris plates 5 and 6 are disposed so that the interior of the main wave guide I is connected to the interior of one branch guide 2 through one set I2, I2' of aligned irises and the clearance space II, and to 'the interior of the other branch guide 3 through th'e other set I3, I3 of aligned irises, and the clearance space II. The branch guides i. `and 3 may be affixed to the iris plate 5 as shown with the long sides of the cross-sections of the former in parallel with each other and with th'e plane of the long dimension of the irises in that plate, and the two branch guides 2 and 3 `are sufficiently separated near switch 4 to provide room between them for the axle I5, its bearing I 5 and the control means (not shown) for driving the axle.

The angle of the sectoral vane I4 is selected so that when it is rotated to a position such that as its leading edge begins effectively to detune one set of aligned irises I2, I2 or I3, lI3 its lagging edge is just leaving that portion of the clearance space between the other set of aligned irises I3, I3 or I2, I2 at which its detuning action effectively' ceases. l

With the vane I4, the clearance space I-I and the irises I2, I2 and`I3, I3' properly proportioned, when the Vane I4 is rotated to a predetermined position between eith'er set of aligned irises I2,

I2 or I3, I3', indicated for the former set in Fig. 5, that set of resonant irises is calpacitively detunedinthemanner described in .the previous discussionot the' valve action, 'sufficiently to substantially block transmission ,or wave energy of the resonant" frequency'v between the' associated branch` guide landthe'main' wave guide l, and the other setfof irises remains tuned so as to allow transmission; in compressed form, of sub stantially all of the wave energy of the resonant frequency from them'ain guide l to the other branch wave guide There will be no appreciable dissipation of th'e wave energy inthe clearance space between the set oi 'resonant irises -rem'ainingvtuned-to .the operating frequency providedthat the -longitudinal and transverse dimensions-"of the rclearance spaceare not eX- cessive.

In the particular' embodimentof the invention illustrated-in Figs. 2 to 5 in which circular metal pipe is employed for the' main wave guide l and rectangular metal pipe for the two branch guides 2 and 3, the impedance mismatchover the frequency band of interest, due to the inability of thel resonant irises Ito correct or'the offset transition fromv circular to rectangular pipe wave guide, may be corrected, as indicated in Fig. 2,- bythe placing of a metal partition I'l with a large circular iris cut in it, across the crosssection of the circular pipe l at-a point approxi mately a half guide-*wavelength away from the resonant irises l2; I3 in the'end iris plate 5. Actually, in practice, the circular iris may also be used to correct for-any additional reflections due to the transition from the rectangular pipe into a radiating surface of an associated antenna (not shown). If such a circular iris is associated with the switch, the useful transmitted band width is somewhat limited; the position of this band, however, maybe varied bychanging the size and location oi' thecircular iris.

As brought -out in the previous discussion, none of the 'dimensions of the switch in accordance with'the invention is critical. The only dimensions which are important for electrical reasons are*v (1) the iris layouts in all dimensions; (2) vane in all dimensions; and (3) all longitudinal dimensions; i. e., thicknesses of iris plates, spacer ring," vane, etc., and' clearances. Experience has shown that these dimensions will be'kept sumciently accurate for good electrical performance yif they are maintained in accordance with moderately accurate mechanical constructions. Also, as 'mentioned' previously,

for greatest efciency all sharp'bounding' surfaces on the irises and the vane` should' be rounded-ofi to reduce corona effects.

A number of switch units of the general type illustrated' inl Figs. 2 to'witlr different dimensions determined by the' wavelength of the wave power tobe switched, were constructed and tested. Theimportant dimensions of one switch unit and of the associated wave guide linesin the embodiment ofthe invention as shown in Figs. 2 and 5, whichrwere constructed for use in antenna lobe "switching for wavelengthsbetween 9.6 and 10.0

centimeters,- were as'` follows:

.i. Circular-'metal pipe of 23e incliinside diameter.

' Branching wave gnides Rectangular metal-pipe-o 1.090 inch x 2.340 inch inside diameter.

. Separation between branch .810 inch.

- wave guidesat switch.

tudinal thickness.

V ane dimensions. Sectoral angle 145, thickness (X094 inch.

These switcheswereexperimentally tested'with both rectangularguides. terminated in their characteristic impedance,v and showedgood switching performance. for the designwavelengthsranging between 9.6 and 10.6 centimeters, .and-.between 9.0 and 9:2 centimeters, respectively. The transmission loss through these switches is very low, being a small fraction of a decibel. All switches were found to be capable of passing in excess of kilowatts.peakpower'ii the'iris and vane edges are carefully polished and iffthe vane is rotated at least -at'a moderately low speed.

Figs. '7 and 8 showcurves which indicate qualitatively the performance of some typical switches. Fig. '7 shows the relative transmission in decibels through'one channel as a function of vane angle rotation in degrees for two typical wavelengths (9.6 and v10.0 centimeters). and' two diierent clearance space diameters (27e-and 2% inches). It is to be' noted that l5 to 2() decibels of blocking is sufiicient in some ofthe typical applications, and the simplified mechanicalconstruction illustrated provides that amount of blocking. Howevenby diminishing the clearance between the vane and the iris plates and. increasing the diameter of the vane, almostany desired amount of transmission blockingmay be secured. Fig. 8 shows the-power division,l relative transmission in` decibels, inthe two branch guides as a functionv of vane rotation anglein degrees for a wavelength centered inthe-operating range ()\=9.8 centimeters) whereithe diameter of clearance space was 2%'inches. -The efficiency, i. e., the Vpercentage of the time. during which substantially all of` the power' is flowing into either one or the other channel, is-about 93 per cent.

It is apparent. that the movement of-.the vane in a switching device. embodying the yprinciples oi the invention may be in a straight linefor vibratory instead of rotary as described and illustrated, in which case a different shape; and size of the clearance space and the vane may. be required to. obtain thedesired switching operations, which might involve the vuse of switchY elements somewhat different from those described above. By suitable control of the vibratory,.rotary or other movement of the vanein a switching. device of the general type described, any desired ytime distribution of the iiow of the. electromagnetic wave energy between the branching wavey guides may be obtained. For example, it maybe arranged to distribute the ow alternately into the branching guides. for desired equaltorhunequal time intervals, byprovidingsuitable motor driven cam arrangements to .maintain aportion of the detuning vane in. the proper position between each set of aligned ir-ises in turn. for-corresponding time intervals. The aligned resonant irises maybe located in adjacent portionsof the side walls of the main and branching wave guides instead of in end cross-section'. plates-as illustrated, in which case thesev adjacent side wall portions would be conductively connected togetherso asA to provide the. narrow clearance space in which the vane rotates, between them. Other modications of the arrangementswhich have been illustrated and described withinzithe spirit and scope ofl the invention will. occur to persons skilled in the art.

What is claimed is:

l.. A switch for controlling the transmission". of wave energy of agiven frequency-betweentwave guide line sections in'la' waveguide transmission .gl system 'comprising'coupling means between said wave guide line sections, including at least one resonant coupling iris normally tuned to said given frequency, so as to efficiently transmit wave energy of that frequency between the coupled .wave guide sections and means mechanically displaceable transversely to said iris for detuning said resonant iris to reduce the transmission of wave energy of said given frequency between said coupled wave guide sections.

2. In combination in a wave transmission system, a main tubular conductor for transmitting electromagnetic wave energy of given frequency, at least one branch tubular conductor for receiving said wave energy and tion of one of its conductive boundary walls ad- 4jacent to a conductive boundary wall of the main conductor, and coupling means between said main and branch conductors such as to conductively connect together the respective adjacent portions of their boundary walls and to provide a relatively small electrically shielded clearance space between them, said coupling means including in said adjacent portions of the boundary walls of the main conductor and each branch conductor respectively oppositely situated irises disposed so as .to connect the interior of the main conductor with the interior of that :branch conductor through said clearance space, each of the oppositely situated irises being proportioned so as to be resonant at said given frequency and in the resonant condition allowing the transmimion of a substantial amount of the wave energy of said given frequency between the connected main conductor and branch conductor, and mechanical means movable to different positions within said clearance space and in a given position with respect to a pair of the oppositely situated resonant irises operating to `detune them suiiiciently to prevent transmission of wave energy of said given frequency between the tubular conductors connected thereby.

3. The combination of claim 2, in whichsaid mechanical means comprises a sectoral vane of conductive material adapted for rotation within said clearance space to and away from said given position with respect to a pair of the oppositely situated irises, and each resonant iris in said adjacent boundary portions of said main and branch conductors comprises a narrow slot of l suitable dimensions and of a curvilinear shape having two portions which are approximately radial with respect to the axis of rotation of said vane.

4. The combination of claim 2, in which each l of said resonant irises in said adjacent boundary portions of said main and branch tubular conductors comprises a narrow slot of suitable dimensions and of a curvature both in the longitudinal and transverse directions such as to enable the passage of high peak electromagnetic wave power whenin the resonant condition.

5. In combination in a wave transmission system, a main tubular conductor transmitting'electromagnetic wave energy of given frequency, one or more auxiliary tubular conductors for` receiving said waveenergyand coupling and switching means therebetween comprising one plate of conductive material conductively attached to the output of said main conductor and extending completely across the cross-section thereof, a second plate of conductive material conductively attached to the inputs of and extending completely across the cross-sections of said one or more auxiliary conductors, means conductively having at least a porlconnecting the two plates together in such mari.- ner asto provide a relatively narrow electrically-shielded clearance space between them, correspondinglysituated identical irises in each plate of` a number equalto the number of auxiliary conductors, each proportioned so as to be resonant to said given frequency, each `set of aligned irises in the two plates being disposed so as toconnectthe interior of said main conductor to thel interior of a diiferent one of said auxiliary conductors through said clearance space, and in the resonant condition being adapted to transmit with little attenuation to the latter auxiliary conductor electromagnetic wave energy of said given frequency from said main conductor, and an element of conductive materialin said clearance space adapted to be rotated therein at least partially in and out of alignment between each set of aligned resonantirises in turnsaid mechanical means in a predetermined alignment position with respect to a set of aligned irises operating to detune that set only, so as to prevent transmission therethrough of any substantial amount of electromagnetic wave energy of said given frequency to the associated auxil- ,the electric vector representing the direction of theline of electric intensity of the electromagnetic wave energy ,transmitted over said main tubular conductor, the dimensions of said slot being proportioned to make it resonant at said given frequency, and said conductive element for detuning the resonant irises comprises a thin vane of conductive material and of suitable shape and dimensions rotatable in said clearance space to said predetermined position between each set of aligned irises.

7. The combination of claim 5, in which each of said resonant irises in said plates comprises a narrow slothaving its long dimension perpendicular tothe lines of electric intensity ofthe electromagnetic wave energy transmitted over said main conductor, and proportioned so as to be resonant at said given frequency, each of said slots being of curvilinear shape having two por- .tions'which are approximately radial with respect to the axis of rotation of said conductive element. l

8: In combination in a dielectric wave guide system, a main tubular conductor transmitting electromagnetic wave energy of given frequency,

` a plurality of other ltubular conductors branching. out from'said main tubular conductor, coupling means between the output of said main conductor andthe inputs of 'said' branching conductors comprising two plates of conductive material respectively extending completely across the cross-section of and conductively attached to the peripheries of adjacent ends of said main tubular conductor and said tubular branching conductors,mean's connecting 4said plates conencara@ energyof said-given :frequency '-incompressed 'fornito the associatedbranching conductor from =the-fmain vconductor,4 anda Vthin-conductive vane 'in -said `clearance spaceadapted for rotation `therein to-precletermined positionsbetween the several-sets of alignedir-isesin saidplates in turn, vsaid-*vanewhen-rotated ytol Vsaid predetermined position betweenone set ofaligned'irises, and awayf4 from-said predetermined position -between anotheresetf operating i to detunev .ther Yi-lrst set v-suiiiciently- .tov prevent substantiallyv any Vtransmission' of electromagnetic Vvwave energy to-'the f associated branch conductor Vfrom saidy main con- -d-uctor, l' while maintaining i. each other set oi Ialigned irisesfin the resonant :condition so as t0 allow transmissiontherethrough :of said energy Aof.l Y- given" frequency f-to' the associated branching condu'ctor -fromsaid mainconductor.

9s Inucombination in a dielectric-wave guide transmission system, a mainlfiollow==metal pipe vftransn'litting electromagnetic wave energy or giv- =en:frequency, twobrarrch hollow metal pipes and coupling and 'switchingmeans between said main and: branch pipes; comprising` twoy metal plates respectively afliXedi .-in conductive .relation y:with and extending completely across-1the crosssec itionszofv adjacent ends. of saidamainpipe and said itwoibranchpipes, respectively, metalll means hold- -ringesaidi two plates fin z conductive relation and forming therebetween: an electrically `shielded narrow. clearance spacci-:two identical i oppositely disposedapertures -iin s.V each iplate, respectively 'aligned'.with ethe corresponding apertures in ithe Aother:qolaten and so positioned that each-aligned setooLapertures connectsv the interior;v of-said fmainfA-pipewithztheinterior. of, a` difierentone of :said ibranch. pipes through, said clearance4 space, .leach aperturezin-,saidi plates f.beinga.-proportioned Lsoil thatiit. isy resonant. at. said given? frequency, a thin sectoral metal vane adaptedi .for :rotation .withinrsaid clearancespace about an axis coaxial iwith 'the'.-longitudinal axisror saidrnainupipe Vpast the xtwoi setszof a. aligned resonant@ apertures f in fturn; said'r vane and-1- saidz irises :being f such .that whenrsaidvaneis rotated to a predetermined position; betweenveither. set of aligned; resonant ,apertures andpaway :from the other setaof. aligned uresonant i. apertures; zit capacitively;rdetunes. said `rst s`et sufficientlygto; v,prevent-.,transmissiorn foi anyl substantial `amount of Waver-energy.v ,of-@said given frequency therethrough to the associated 1 branch r-pipe'lfrom. said-,main apipe,` andmaintains saidz other; .setn ofi-resonant ,irises tuned to allow ,'transmission.therethroughtto. saidv other branch .pi-peizof substantially, 'all of fthe-:wave.energy of nsaid given f frequency l received over.: said .main

pipe.

w10. f: Thea-combination,- of.r claim: 9, in `.which the thickness vof:each-,ofsa-id meta-l-platesisveryismall @compared-tothe;wavelength of said=electromag netic wave energy of given frequency; and such. as ftoaprovidav a :desired sharpness ofthe: drequency ileponseor;saidresonantv aperture.

11.The combination :of claim =l.9,f. in: which the EWG; resonant aperturesinaeachzplatecomprise .op- I `positely fg-disposed` l curvilinear. narrow,- .fslots i. the curvaturenbeingf suchfsask @to iprovide :fora each: slot 12 two portions directed. approximately :radially to- -ward the axis of saidmainpipe.

l l2. The combination offclaimz 9 1 in lwhichcs'aid mainlpipe is of .circular cross-section andea'ch of said branch pipes is-of .rectangular cross-section, and to correct'for the impedance mismatchduelto the transition from circular to'rectangular pipe, a metalpartition'with a circular orifice ofJ suitable dimension is placed across the cross-sectionA of the circular pipe at a distancelof approximately a half wavelengthlfrom its end plate.

13;Y Inra vwave guide system,A `two r`hollow -conductor wave guides joined endfto end'iorthroufgh transmission of electrically guided-*wavesfromthe vinterior ofone guide-to Vlthe interior 'of-theother, a conducting transverse platelo'catedbetween lsaid guides yhaving a parallel 'tuned' :slot dimensioned to provide selective transmission -of waves-'vot a given-frequency romoneguide-into the other, and means for capacitivelydetuningsaid slot to shift its' resonant'l vfrequency so` as4 tol substantially prevent transmission ztherethrough of^wave energy of said given frequency comprising afmetallic vaneV movableL transversely` a'crosssaldifslot toagiven position.

14. The-'invention according -to claim"'l3"in which said slot isof curvilinearv coniiguration, shaped to be symmetrical about agiven'-'medial Iline soas to have on each'side of ysaid line a portion that extends 'for a distancein a substantially radial*direction-with respect tothe axis ofzfthe guide, andin which said vane in oneposition covers both of` said two-portions ofsaidslotY andin another position uncovers Asaid two portions.

- 15J- In a wave Ltransmission system, vtwo` hollow conductor'wave guidesdisposed end toA endywave coupling means'l between said; guides: comprising two plates of conductive material respectively vextending across and conductivelyaiixedytoxaf different one of the adjacent ends ofjthe two guides, means connectingI ,said plates conductively ltogether so as to form an electricallyjshieldedclearance-space between'them, each of said plates `having ai parallel tuned slot 'therein suitablyjdimensioned and located so as to enable selective. transmission of electromagnetic wave energy of a given `frequency between the interiors of the two wave ,guidesjthrough' 'the two slots and ,said clearance Ispace, and means to capacitively detune said slots so as to substantially prevent. transmission of wave energy of said given'irequency between said tguides comprising a metallic vane movable' across said clearance spacev to a given position between said slots.

"WAl'tREN AKTYRRELL.

REFERENCES' CITED A'Ihefol1owir1gV references,j are of: recorrl'fin;v :the

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